1. Field of the Invention
The present invention relates to a method for producing a high purity 1,1-bis(4-hydroxyphenyl)cyclohexane that is useful as a material for various polymers, such as aromatic polycarbonates, aromatic polyether sulfones, aromatic polyether ketones, and aromatic polyether imides, advantageously on an industrial scale with improved production yield and efficiency.
2. Description of the Related Art
A 1,1-bis(4-hydroxyphenyl)cyclohexane is a kind of bisphenol and generally obtained by reacting cyclohexanone and a phenol in the presence of an acid catalyst. In order to obtain a high purity 1,1-bis(4-hydroxyphenyl)cyclohexane on an industrial scale, there has been a conventionally known method in which, for example, cyclohexanone and a phenol are reacted in the presence of an acid catalyst, a reaction product obtained is neutralized with an alkali, the resulting 1,1-bis(4-hydroxyphenyl)cyclohexane is primarily crystallized and filtered, the reaction product is washed with methylene chloride, and then recrystallized from a mixed solvent of methanol and water to obtain a 99.2% pure 1,1-bis(4-hydroxyphenyl)cyclohexane. Further, it is known that the abovementioned reaction product can be washed with methylene chloride and dried to similarly obtain a high purity product (see Japanese Patent Application Laid-open No. 64-22833).
On the other hand, it is also known that a 99.3% pure 1,1-bis(4-hydroxyphenyl)cyclohexane can be obtained by the mixed crystallization of a 1,1-bis(4-hydroxyphenyl)cyclohexane and a phenol followed by the heating in vacuum (see Japanese Patent Application Laid-open No. 5-78270).
In recent years, with the expansion of the use of 1,1-bis(4-hydroxyphenyl)cyclohexanes, there has been a strong demand for producing products having further higher purity on an industrial scale with further improved production yield and efficiency. However, the abovementioned methods cannot meet such a demand, and furthermore, there has been so far no measure reported regarding the removal of a very small amount of metal impurities in a reaction product, which is derived from an alkali such as sodium hydroxide used to neutralize a resulting reaction mixture.